Far-Infrared Spectrum, ab Initio, and DFT Calculations and Two-Dimensional Torsional Potential Function of Dimethylallene (3-Methyl-1,2-butadiene)
Far-Infrared Spectrum, ab Initio, and DFT Calculations and Two-Dimensional Torsional Potential Function of Dimethylallene (3-Methyl-1,2-butadiene)
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二甲基丙二烯（3-甲基-1,2-丁二烯）的远红外光谱、从头计算和 DFT 计算以及二维扭转势函数
DOI：
10.1021/jp993376b
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发表时间：
2000
影响因子：
2.9
通讯作者：
J. Durig
中科院分区：
文献类型：
--
作者：
S. Bell;P. Groner;and Gamil A. Guirgis;J. Durig
测定了气态二甲基烯(3-甲基-1，2-丁二烯)、(CH3)2CCCH2的远红外和红外光谱，以及化合物在三个物相中的拉曼光谱。以红外谱带轮廓、拉曼消偏率和从头计算预测的谐波频率和强度为判据对光谱进行了指认。通过对具有两个周期大幅度运动的分子的有效转动哈密顿量进行频率拟合，从先前发表的微波光谱中确定了基态和一个扭转激发态的扭转能级分裂。利用裂解和远红外光谱数据，推导了二甲基烯的二维扭转势函数。该函数的有效势垒为V_3Jeff=726(4)cm~(-1)，与微波分析的结果以及用多种从头算方法(其中包括B3LYP/6-31G(D)和MP2/DZ(D))计算的势函数进行了比较。
The far-infrared and infrared spectra of gaseous dimethylallene (3-methyl-1,2-butadiene), (CH3)2CCCH2, were measured as well as the Raman spectra of the compound in all three physical phases. The spectra were assigned using infrared band contours, Raman depolarization ratios and ab initio predicted harmonic frequencies and intensities as criteria. The torsional energy level splittings were determined for the ground state and one torsional excited state from previously published microwave spectra by fitting the frequencies to an effective rotational Hamiltonian for molecules with two periodic large-amplitude motions. The splittings and the data from the far-infrared spectrum were used to derive the two-dimensional torsional potential function of dimethylallene. This function with an effective barrier V3eff = 726(4) cm-1 is compared with the results from the microwave analysis and with the potential function calculated by a number of ab initio methods (among them B3LYP/6-31G(d) and MP2/DZ(d)).